Russia would consider using force if necessary to respond if the US put a combat weapon into space, according to a senior Russian official.

According to a New York Times report yesterday, the Bush administration was moving towards implementing a new space policy that would move the US closer to placing offensive and defensive weapons in space.

Russia, China and many US allies oppose any weaponisation of space, partly out of concerns that it would lead to an extremely expensive post-cold war arms race.

Vladimir Yermakov, senior counsellor at the Russian embassy in Washington, on Tuesday told a conference on space militarisation that Russia was working through diplomatic channels to urge the US not to move towards fielding weapons in space. But he said Russia would have to react, possibly with force, if the US successfully put a "combat weapon" in space.

In an interview yesterday, Mr Yermakov emphasised that Russia's priority was to solve the problem diplomatically. Russia has voluntarily declared that it will not be the first country to place weapons in space in an effort to encourage the US to move away from space weaponisation.

Force is "not a subject for discussion right now", Mr Yermakov said. "It depends on what happens, and why it happens, upon what agreements we have with the US government, and what understandings we have with the US government."

He added: "Our policy is not to create situations that would lead [to] confrontation. If we don't find such understandings with the US government, and we find ourselves in a situation where we need to react, of course we will do it."

The White House denied that President George W. Bush was about to sign a new directive on space policy that would permit the weaponisation of space.

"The US has no intention to weaponise [space]," said a senior administration official. "The policy review was not initiated at the request of the air force or the department of defence, and the policy, while not yet finalised, would not represent a substantial shift in American policy."

Any new policy would replace a 1996 policy implemented by the Clinton administration calling for a less militaristic approach to space. The 1967 treaty on outer space prevents countries from putting only weapons of mass destruction in space. Other countries are concerned that some of the weapons being considered by the US could be considered new types of WMD.

One weapon the air force would like to develop is the Common Aero Vehicle, which would give the US the ability to launch precision-guided strikes at any point on the globe within a short time frame. The internal US debate over whether the Pentagon needs to put weapons in space gained momentum in 2001 following the conclusions of a commission that warned of the possibility of a "space Pearl Harbor" that could destroy US commercial and military satellites.

"If the US is to avoid a 'space Pearl Harbor', it needs to take seriously the possibility of an attack on US space systems," said the commission, which was chaired by Donald Rumsfeld before he became US defence secretary.

The commission's report concluded that the US needed "superior space capabilities" to prevent and defend against hostile acts "in and from space".